Apical Pressure Research Articles

Numerical investigation and optimization of innovative root canal irrigation needles with composite flow control structures.

Needle syringe irrigation is frequently used in root canal therapy, and the flow pattern during irrigation can be efficiently manipulated by means of passive flow control technique, resulting in expected irrigation performance improvement. Therefore, novel needles with composite flow control structures are numerically investigated and optimized in this study. Based on the 30G needle, six single/double side-vented needles with dimple and protrusion are proposed. Two flow rates in line with clinical applications, 5.3 and 8.6 m/s, are used in the analysis. Three performance parameters are investigated. The safety of the irrigation system is evaluated by the root canal apical pressure, whereas the irrigant extension and the flushing efficiency are evaluated by the extending depth and the effective cleaning area, respectively. The results demonstrate that the shear stress of the double-side-vented needle is higher while the irrigant extension is enhanced with a dimple structure. The performance of the double-side-vented needle with a dimple is superior to that of other designs, with up to 33% improvement in extending depth and a 22% increase in effective cleaning area over the prototype. New needles do not raise risk of irrigant extrusion. Furthermore, the effect of dimple depth and outlet angle are investigated. The needle with a dimple of 0.04 mm depth shows the highest extending depth within the confines of the investigation. The effective cleaning area is significantly influenced by the needle outlets, and the effective cleaning area expands with an increase in needle outlet angle, while the extending depth gradually declines.

The effects of aperture position and length in side-vented needles on root canal irrigation: A computational fluid dynamics study

IntroductionRoot canal irrigation is crucial for infection control during root canal treatment. Side-vented needles for positive pressure irrigation are commonly used in clinical practice. However, variations in needle design among manufacturers can impact the fluid dynamics of irrigation. This study aims to use computational fluid dynamics to explore the flow characteristics of different needle aperture lengths and positions, and their effects on the effectiveness and safety of irrigation, using a validated passive scalar transport numerical model. MethodsThe validation of the CFD irrigant model was achieved by comparing it with an in vitro irrigation experiment model. The CFD model used scalar concentration, while the in vitro experiment model used red dye tracing. Using a standard 30G side-vented needle as a reference, virtual needle models featuring four aperture lengths and three positions were created. These virtual irrigation needles were then placed in two root canal geometries for CFD simulation to evaluate fluid exchange capabilities and related fluid dynamic parameters. ResultsThe results of the CFD simulation, using a scalar transport model, closely matched the in vitro tracer tests for irrigation experiments across seven root canal geometries. The CFD analysis indicated that positioning the aperture lower increased the irrigant exchange distance. Notably, decreasing the aperture length to 0.25x, and positioning it at the lower end of the needle significantly increased exchange distance and shear stress, while reducing apical pressure. ConclusionsThese results indicate that the position and length of the aperture affect the exchange distance of irrigant flow, wall shear stress, and apical pressure. The CFD validation model for scalar transport, based on a steady state, can function as a valuable tool for optimizing the side-vented needle in research. Further research on the design of side-vented needles will enhance the understanding of flow characteristics beneficial for irrigation efficiency in clinical practice.

Irrigant dynamics of a back-to-back double side-vented needle in root canals with various tapers: a computational fluid dynamics study

Understanding the apical pressure and irrigant flow patterns in root canals is crucial for safe and effective irrigation. Therefore, this study aimed to assess the flow characteristics of irrigants in root canal models with varying tapers during final irrigation by employing various needle designs, including a back-to-back double-side-vented needle, through computational fluid dynamics. The root canal model was configured as a closed geometrical cone with a simulated apical zone (size 30) and features tapers of 4%, 6%, and 8%. Three needle types—open-ended needle (OEN), single side-vented needle (SSVN), and double side-vented needle (DSVN)—were investigated. The results indicated that for the 4% taper models, the open-ended needle generated the maximum apical pressure, followed by the double side-vented needle and the single side-vented needle. However, in the 6% and 8% tapering root canal models, the double-side-vented needle applied the lowest maximum apical pressure. Consequently, the DSVN can pose a risk for irrigant extrusion in minimally prepared canals due to heightened apical pressure. In wider canals, the DSVN exhibited lower apical pressure. The maximum irrigant replacement was observed with OEN compared to that of the closed-ended group for both flow rates. Additionally, compared with OENs, closed-ended needles exhibited nonuniform and lower shear wall stress.

PERFORMANCE IMPROVEMENT OF TRANSIENT PULSATING FLOW IN ROOT CANAL IRRIGATION AND FLOW MECHANISM ANALYSIS

Inflow conditions dominate the process of root canal irrigation, and the application of pulsating inflow in dentistry is necessary to be explored due to its mass transfer enhancement capability. A prepared root canal model with a 30G side-vented needle is numerically investigated under pulsating inflow with different frequencies and amplitudes. Root canal apical pressure, extending depth, and effective cleaning area are adopted to evaluate the safety, mass transfer capacity, and clean efficiency of the irrigation system. Time-averaged results show that the irrigation performance is improved with pulsating flow maintaining safety. Compared with steady cases, the extending depth and effective cleaning area are increased by up to 43.6% and 11.42%, respectively. Three typical cases with significant improvement are selected for transient analysis. Transient results show that the apical pressure and extending depth have instant response features, while the effective cleaning area has a time-lag response characteristic. It is convinced that the transient characteristic of the system results from the coupling effects of the pulsating effect, instantaneous flow rate, and Coanda effect. The internal flow distribution of root canal system is prompted under the optimal parameters combinations of pulsating conditions, in which mass transfer capacity and clean efficiency are enhanced with guaranteed safety.

Computational fluid dynamics investigation on the irrigation of a real root canal with a side-vented needle

BackgroundRoot canal therapy is one of the main treatments for root canal diseases, and effective irrigation is the key to successful treatment. Side-vented needle is one of the commonly used needle types in clinic. In the real root canal, due to the influence of the curvature of the root canal, the irrigation flow field in different needle directions shows obvious differences. At the same time, changes in root canal curvature and working depth will lead to changes in irrigation efficiency and the flow field. Both the mainstream of the irrigation flow and the shear stress near the wall changes significant. Consequently, either the replacement in the root canal or the removal efficiency of the smear layers is apparently modified.Materials and methodsIn this paper, the permanent root canal of the maxillary first molar prepared until 15/04 were scanned by micro-CT, and then imported into the software for 3D reconstruction. The key parameters of flushing efficiency of 30G side needle at different working depths of 4.75 mm, 5 mm, 5.25 mm and 5.5 mm were compared. Meanwhile, the simulated models with different curvatures of 0°, 5°, 10°, 20° and 30° based on the real root canal were reconstructed to investigate the curvature effect on the irrigation efficiency.ResultsThe results show that moderate working depth (such as 4.75 mm and 5.25 mm in present paper) helps to improve the replacement capacity of irrigation flow. At the same time, the apical pressure decreased as the working depth increased. The curvature of the root canal seriously affects the removal depth of the smear layers of the root canal. A root canal with a large curvature (especially 20° and 30°) can significantly improve the difficulty of irrigation.Conclusions(1) Moderate working depth helps to improve the displacement capacity, the ERD of the irrigation flow is generally improved at the working depths of 4.75 mm and 5.25 mm, and the apical pressure will decrease with the increase of working depth. (2) The large curvature of the root canal can significantly improve the difficulty of irrigation. The curvature of the root canal can severely influence the removal depth of the smear layer on the wall. It can be found both the span and the depth of the ESS for little curvatures (5° and 10°) root canals are higher than those for large curvatures (20° and 30°).

Multimethod analysis of large- and low-tapered single file reciprocating instruments: Design, metallurgy, mechanical performance, and irrigation flow.

To compare eight large- and low-tapered heat-treated reciprocating instruments regarding their design, metallurgy, mechanical properties, and irrigation flow through an in silico model. A total of 472 new 25-mm E-Flex Rex (25/.04 and 25/.06), Excalibur (25/.05), Procodile (25/.06), Reciproc Blue R25 (25/.08v), WaveOne Gold Primary (25/.07v), and Univy Sense (25/.04 and 25/.06) instruments were evaluated regarding their design (stereomicroscopy, scanning electron microscopy, and 3D surface scanning), metallurgy (energy-dispersive X-ray spectroscopy and differential scanning calorimetry), and mechanical performance (cyclic fatigue, torsional resistance, cutting ability, bending and buckling resistance). Computational fluid dynamics assessment was also conducted to determine the irrigation flow pattern, apical pressure, and wall shear stress in simulated canal preparations. Kruskal-Wallis and one-way anova post hoc Tukey tests were used for statistical comparisons (α = 5%). Instruments presented variations in blade numbers, helical angles, and tip designs, with all featuring non-active tips, symmetrical blades, and equiatomic nickel-titanium ratios. Cross-sectional designs exhibited an S-shaped geometry, except for WaveOne Gold. Univy 25/.04 and Reciproc Blue displayed the smallest and largest core diameters at D3. Univy 25/.04 and E-Flex Rec 25/.04 demonstrated the longest time to fracture (p < .05). Reciproc Blue and Univy 25/.04 exhibited the highest and lowest torque to fracture, respectively (p < .05). Univy 25/.04 and Reciproc Blue had the highest rotation angles, whilst E-Flex Rec 25/.06 showed the lowest angle (p < .05). The better cutting ability was observed with E-Flex Rec 25/.06, Procodile, Excalibur, and Reciproc Blue (p > .05). Reciproc R25 and E-Flex Rec showed the highest buckling resistance values (p < .05), with WaveOne Gold being the least flexible instrument. The impact of instruments' size and taper on wall shear stress and apical pressure did not follow a distinct pattern, although Univy 25/.04 and E-Flex Rec 25/.06 yielded the highest and lowest values for both parameters, respectively. Low-tapered reciprocating instruments exhibit increased flexibility, higher time to fracture, and greater angles of rotation, coupled with reduced maximum bending loads and buckling strength compared to large-tapered instruments. Nevertheless, low-tapered systems also exhibit lower maximum torque to fracture and inferior cutting ability, contributing to a narrower apical canal enlargement that may compromise the penetration of irrigants in that region.

Assessment of Apical Pressures in Single and Joining Canals - An Ex Vivo Study Based on Computational Fluid Dynamic Analysis.

Computational fluid dynamic analysis (CFD) is claimed to be a reliable tool for analysing the fluid flow and the generated apical pressures in the simulated root canal. The current study aimed to analyse the apical pressures in extracted teeth with single and joining canals. Forty-six freshly extracted teeth were collected for the present study. The power was set at 95%, with an effect size of 0.55 (1-β=95%, α=0.05). Once the root canal anatomy was confirmed with cone-beam computed tomography (CBCT), they were divided into two groups: group I: mandibular second premolars with Vertucci type-I (n=23), and group II: maxillary second premolars with Vertucci type-II (n=23). The instrumentation of the specimens was carried out to a 0.04-taper using rotary instruments. A post-instrumentation CBCT was obtained, and computer-aided design models were obtained. The CFD simulations were then con- ducted with simulated 30-gauge side vented needles at 25, 50, and 75% short of the working length (WL). Group I recorded significantly (p<0.05) higher apical pressures at needle positions 25% short of the WL. However, no significant differences were elicited in the groups at other needle positions. Single canal specimens recorded higher apical pressures at needle positions 25% short of the WL. However, no differences were elicited between single and joining canals at higher needle positions.

Rheological properties and handling characteristics of four injectable calcium hydroxide pastes.

The aim of this study was to investigate the rheological properties and handling characteristics of four brands of injectable calcium hydroxide pastes (Calcipex II, CleaniCal, DiaPaste, Well-Paste). Shear viscosity was measured with a rotational rheometer. A universal mechanics analyzer assembled in the laboratory was used to quantify the force for extrusion and extruded weight of the materials. The apical pressure during injection into an artificial root canal was measured using a pressure sensor. All materials exhibited pseudoplastic behavior. The force for extrusion was highest for DiaPaste, and lowest for CleaniCal, while the extruded weight was lowest for DiaPaste and highest for CleaniCal (p<0.05), indicating a need for caution when using CleaniCal. However, the pressure generated at the apex may vary depending on the shape, and taper of the needle tip, as well as the viscosity of the materials.

Positive Pressure and Negative Pressure Irrigation Dynamics with Different Needle Designs Using Computational Fluid Dynamics

This study aimed to investigate the irrigation dynamics of the positive pressure side-vented (SV) needle, EndoVac (micropores) needle and modified apical negative pressure (mANP) open-ended needle using computational fluid dynamics (CFD). A simulation of a prepared root canal (conical frustum) of 15 mm length with an apical diameter of 0.40 mm following Protaper F4 apical preparation was created using three-dimensional (3D) CAD software. The 3D simulated needle of SV 30G needle, EndoVac with micropores needle and mANP, 30G flat open-ended needle were also created. The irrigation dynamics were evaluated through transient CFD simulations. In addition, the irrigation dynamics of mANP at 0.2 mm, 0.5 mm, and 1.0 mm short from the working length were also assessed. The EndoVac and mANP showed negative apical static pressure and streamline patterns able to reach the apical region, thus indicating negligible extrusion. Meanwhile, SV showed positive apical static pressure and almost nonexistent streamlines beyond the needle tip. The SV showed the highest wall shear stress (WSS) magnitude of 1030Pa whereas Endovac (161 Pa) and mANP1 (258 Pa). However, SV revealed lower average WSS (10 Pa) compared to mANP1 (13 Pa) and mANP2 (11 Pa). This is due to SV developed a localised maximum WSS opposite the open vent area only therefore, uneven distribution of WSS. The EndoVac system developed a localised maximum WSS in the pair of micropores furthest away from the apical. CFD analysis of the EndoVac, mANP and SV showed different technique approach, needle design and needle depths insertion affect the irrigation dynamics pattern and magnitude.

Clinical efficacy of endodontic protocols on reducing cultivable bacteria and endotoxin in infected root canal in patients submitted to head and neck radiotherapy: a randomised clinical trial.

Assess the efficacy of biomechanical preparation using a reciprocating system followed by final irrigation protocols, then intracanal medication, on reducing endotoxins and cultivable bacteria of infected teeth in irradiated patients. Twenty-two infected single-rooted canals in patients submitted to head and neck radiotherapy were prepared by reciprocating motion and 2.5% NaOCl. Patients were randomly divided into two groups of 11 patients before the final irrigation protocol: apical positive pressure (APP) or passive ultrasonic activation (PUA). Both groups were treated in two sessions, using Ca(OH)2 as intracanal medication for 14 days. Root canal content sampling was performed after canal access (S1), after biomechanical preparation plus the irrigation protocol (S2), and after intracanal medication (S3). Chromogenic limulus amoebocyte lysate assay measured endotoxin levels (EU/mL), and bacterial load was determined by culture techniques (CFU/mL). Treatment protocols reduced bacterial counts after S2 in both groups (p = 0.01). S3 differed from S1 (p = 0.01), but not from S2 (p = 0.4). Endotoxin levels were reduced in both groups after S2 (P = 0.03) and were lower in S3 than in S2, with significant differences in the APP group (p = 0.03). Biomechanical preparation using a reciprocating system and 2.5% NaOCl in irradiated teeth, followed by the irrigation protocol (APP or PUA), demonstrated efficacy in reducing endodontic contaminants. Ca(OH)2 as intracanal medication should be performed in irradiated patients with infected root canals. This clinical study demonstrated that endodontic treatment in irradiated patients is efficacious at reducing bacterial load and endotoxin levels.

Efficiency of syringe irrigation in chemomechanical root canal treatment

Syringe irrigation is still the most shared clinical procedure for delivering endodontic irrigants. The shape and size of apical preparation should be matched to the individual morphological profile of the root canal to perform adequate cleaning. The irrigant flow beyond the needle tip seems to be influenced by the flow rate rather than the individual intra-barrel pressure developed within syringe. Proper selected size of the irrigation needle adapted to corresponding apical preparation size and the multiple maneuvers of irrigation should result in an expected cleaning efficacy. Irrigant replacement, shear stress and apical pressure are crucial cleaning factors in mutual contradiction. Presently no consensus came out to establish to whom should be forwarded the main concern.

Farklı İğne Tasarımlarının Diş Kanalı İrrigasyonu Üzerindeki Etkilerinin Hesaplamalı Akışkanlar Dinamiği ile İncelenmesi

This study aims to investigate the effects of irrigation needles geometries on the flow inside the root canal and compare their irrigation performances based on Computational Fluid Dynamics (CFD) analyzes. CFD simulations of three commonly used close-ended irrigation needles were performed for various inlet Reynolds numbers and working lengths. Their irrigation performances were evaluated based on apical pressure and wall shear stress. The flow was assumed to be incompressible, turbulent and steady at all inlet Reynolds numbers. The closed-ended needles showed similar limited irrigant penetration toward the apex. Among all configurations, the Model C outperforms others as it provides the highest wall shear stress around the needle tip and the lowest apical pressures in the apical foramen, which reduces the risk of apical extrusion. The needle tip designs influence important parameters for the effectiveness and safety of the irrigation process.

Characterization of four heat-treated reciprocating instruments: Design, metallurgy, mechanical performance, and irrigation flow patterns.

To compare the design, metallurgy, and mechanical properties of four heat-treated reciprocating instruments coupled with the evaluation of the irrigation flow using an in silico model. New EdgeOne Fire Primary, Easy-File Flex Regular 25, WaveOne Gold Primary and Reciproc Blue R25 instruments (n = 124) were initially evaluated regarding their design through stereomicroscopy, scanning electron microscopy and 3D surface scanning. In addition, energy-dispersive X-ray spectroscopy was utilized to determine their elemental composition, and differential scanning calorimetry tests to evaluate their phase transformation temperatures. Their mechanical performance was further assessed through torsional and bending tests. Using scans obtained from a real tooth and the instruments, a computational fluid dynamics assessment was conducted to determine the irrigation flow pattern, apical pressure, and wall shear stress in simulated canal preparation. Mood's median and One-way anova post hoc Tukey tests were used for statistical comparisons (α = 5%). Reciproc Blue exhibited a superior number of blades (n = 8), whereas EdgeOne Fire had the highest overall volume (4.38 mm3 ) and surface area (32.32 mm2 ). At the 3-mm axial level, EdgeOne Fire displayed the lowest core diameter (0.13 mm), while Reciproc Blue had the highest (0.16 mm). All blades were symmetrical, and the tips of the instruments were non-active but differed from each other. The most irregular surfaces were observed in EdgeOne Fire and Easy-File Flex. All instruments were manufactured from nickel-titanium alloys and exhibited distinct phase transformation temperatures. WaveOne Gold and Reciproc Blue demonstrated the highest maximum torque values (1.87 and 1.62 N cm, respectively), while the lowest was observed on EdgeOne Fire (1.21 N cm) (p < .05). The most flexible (p < .05) were EdgeOne Fire (angle of rotation: 602.6°; maximum bending load: 251.4 g.f) and Reciproc Blue (533.2° and 235.6 g.f). There were no significant differences observed in the irrigation flow among the four domains generated by the tested instruments. Despite observing variations in the design, phase transformation temperatures, and in the torsional and bending test outcomes among the four heat-treated reciprocating instruments, no significant differences were found in the irrigation flow pattern among the different groups in the simulated root canal preparations.

Influence of needle design and irrigation depth in the presence of vapor lock: A computational fluid dynamics analysis in human oval roots with apical ramification.

This paper aims to study the removal of a vapor lock located in the apical ramification of an oval distal root of a human mandibular molar, simulating different needles and irrigation depths with computational fluid dynamic. A geometric reconstruction of the micro-CT of the molar shaped up to a WaveOne Gold Medium instrument was used. A vapor lock located in the apical 2 mm was incorporated. Geometries with positive pressure needles (side-vented [SV], flat or front-vented [FV] and notched [N]) and the EndoVac microcannula (MiC) were created to run the simulations. Irrigation key parameters (flow pattern, irrigant velocity, apical pressure, wall shear stress) and vapor lock removal were compared among the different simulations. Each needle behaved differently that is, FV removed the vapor lock from one ramification and had the highest apical pressure and shear stress values; SV removed the vapor lock in the main root canal but not in the ramification and reached the lowest apical pressure from the positive pressure needles; N was not able to completely remove the vapor lock and showed low apical pressure and shear stress; MiC removed the vapor lock from one ramification, had negative apical pressure and the lowest maximum shear stress. The main conclusion is that none of the needles showed complete removal of vapor lock. MiC, N, and FV were able to partially remove the vapor lock from one out of the three ramifications. However, SV needle was the only simulation that showed high shear stress with low apical pressure.

Negative Pressure Irrigation Dynamics between Two Needle Designs using Computational Fluid Dynamics

Objective: This study aimed to investigate the irrigation dynamics of the EndoVac and modified apical negative pressure (mANP) using Computational Fluid Dynamics (CFD) for application in endodontic irrigation. Methodology: A simulation of a prepared root canal (conical frustum) of 12 mm length with an apical diameter of 0.40 mm following Protaper F4 apical preparation was created using three-dimensional (3D) CAD software. 3D simulated aspiration needles (EndoVac, micropores needle) and (mANP, 30G flat open-ended needle) were also created. The irrigation dynamics were evaluated through transient CFD simulations. In addition, the irrigation dynamics of mANP were also assessed at three different needle depths of insertion. Results: The EndoVac and mANP streamlines pattern showed irrigants able to reach the apical end. Both needle designs demonstrated negative static apical pressure. The mANP using an open-ended needle design revealed a higher average WSS magnitude in all three different needle depths of insertion compared to the EndoVac. Conclusion: CFD analysis of the EndoVac and mANP revealed that different needle designs and needle depth insertion affect the irrigation dynamics pattern and magnitude in a simulated root canal. The open-ended needle design of mANP1 contributed to the higher WSS magnitude, discharge coefficient, and apical static pressure compared to the EndoVac.

Insights of fluid dynamics in an optimally shaped root canal system

Dear Editor, Fluid flow patterns are investigated and understood only at in vitro levels through laboratory-based studies.[1] Various physical parameters play a crucial role in enhancing the irrigant flow in a prepared canal space. Ideally, the physiological limit of the irrigant must be restricted within the canal space and also it might not be clinically possible to specifically determine the exact value when the irrigant exceeds the optimal flow rate. Laboratory-based studies proved 1–4 ml/min to be the optimal flow rate to prevent inherent extrusions and apical pressures.[2,3] Although the in vitro literature focused more on syringe needle irrigation,[1] in routine clinical practice with the use of manual needle irrigation, it might not be possible to obtain maximum disinfection. The current clinical literature is now more focused on the efficacy of activation systems with less preference to manual irrigation techniques.[4,5] Previous study showed 30G side vented needles to be the most frequently used[6] and induce the least pressure at a specified irrigant flow rate.[1] However still, the existing literature evidence has not given insights into the fluid dynamics of various activation systems and also the complex nature of the irrigant flow pattern is unexplored. As the irrigant flow rate cannot be standardized on activation, there is an urge for future research which specifically investigates the irrigation dynamics of using various activation devices. Hence, the tendency of irrigant extrusions with various activation devices and the complexity of fluid dynamics are yet to be investigated, especially considering the various physical parameters, including the velocity, turbulence, and shear wall stress considering the induced apical pressures. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

OUTPATIENT PERCUTANEOUS ULTRASOUND-GUIDED FLEXOR TENOTOMY FOR NEUROPATHIC APICAL TOE ULCERS

Percutaneous flexor tenotomy involves cutting the flexor digitorum tendons to correct claw toe deformity to treat apical pressure areas and prevent subsequent infection in patients with peripheral neuropathy. Performing this under ultrasound guidance provides reassurance of complete release of the tendon and increases procedural safety.This study is a retrospective case series evaluating the effectiveness, safety, and patient satisfaction of performing percutaneous ultrasound-guided flexor tenotomy in an outpatient setting. People with loss of protective sensation, a digital flexion deformity, and an apical toe ulcer or pre-ulcerative lesion who presented to our institution between December 2019 and June 2022 were included in this study. Participants were followed-up at a minimum of 3 months. Time to ulcer healing, re-ulceration rate, patient satisfaction, and complications were recorded. An Australian cost analysis was performed comparing this procedure performed in rooms versus theatres.There were 28 ulcers and 41 pre-ulcerative lesions. A total of 69 tenotomy procedures were performed on 38 patients across 52 episodes of care. The mean time to ulcer healing was 22.5 +/- 6.4 days. There were 2 cases of re-ulceration. 1 patient sustained a transfer lesion. There were four toes that went onto require amputation, all in the setting of pre-existing osteomyelitis. 94% of patients strongly agreed that they were satisfied with the outcome of the procedure. Costs saved were estimated to be $1426.Flexor tenotomy is a minimally invasive procedure that can be performed in the outpatient setting, and therefore without delay to treatment, reducing risk of ulcer progression and need for subsequent amputation. This is the first study to report on flexor tenotomy under ultrasound-guidance.Ultrasound-guided percutaneous flexor tenotomy is safe and effective, with high patient satisfaction and low recurrence rates. This performance in the outpatient setting ensures significant time and cost savings for both the practitioner and patient.

Flow characteristics of positive and negative pressure irrigation in an immature tooth - A computational fluid dynamics study.

This study aims to investigate the irrigation dynamics in an immature tooth during positive and negative pressure irrigation using a computational fluid dynamics (CFDs) model. Cone-beam computed tomography scan of the maxillary central incisor with Cvek's stage III root development was used for the reconstruction of the root canal geometry. The computer-aided design models of open (front vent and notched) and closed (side vent [SV]) needles were positioned inside the root canal at two penetration depths, i.e., 3 mm and 1 mm short of apex. The negative pressure microcannula (MiC) was positioned at the level of the root apex. A prevalidated CFD model was used to simulate endodontic irrigation. The irrigant velocity in the apical root canal beyond the needle tip exceeded 0.1 m/s. As the needles were positioned closer to the apex, the wall shear stress (WSS) increased for the open-ended needles and decreased for the SV needle. MiC produced the lowest WSS. The mean apical pressure produced by the SV needle and MiC were below the critical threshold for periapical extrusion. The SV needle inserted within 1-3 mm of root apex during endodontic irrigation in an immature tooth allows adequate irrigant exchange with minimal risk of periapical extrusion.

Conservative Approach in the Management of Lesser Toe Deformities in Older Adults.

Toe deformities are common foot abnormalities in older adults, contributing to functional disability, loss of balance, falls, and pressure lesions. The aim of this study was to evaluate the effectiveness of the custom-made molded silicone toe prop in distributing apical and metatarsophalangeal joint peak plantar pressures and force-time integral in toe deformities, including hammertoes and claw toes, and to observe any difference in pressures between flexible and rigid toe deformities. A prospective quasi-experimental pretest/posttest study was conducted including 20 "healthy" older adults with a hammer or claw toe at the second digit. Ten subjects presented with a flexible toe and 10 subjects presented with a rigid toe. A molded silicone toe prop was devised for each participant. Dynamic plantar pressure measurements were taken/recorded before applying the toe prop and after the toe prop was placed under the toe. Significant differences in mean peak plantar pressure and pressure-time integral were observed at the apex of the second toe in both the flexible and rigid toe deformity when using a molded silicone toe prop. At the metatarsophalangeal joint, pressures were significantly reduced in the rigid toe deformity but not in the flexible toe deformity. Silicone molded toe props were found to be effective in reducing peak pressure and pressure-time integral on the apex of the second digit in participants with both flexible and rigid claw or hammertoe deformity. Lesser toe deformities may be the cause of several foot complications, including pain on walking, corns, difficulty in wearing footwear, possible ulcerations caused by increased pressure at the apices of the toes, and other comorbidities, that could possibly lead to falls in older adults and thus need to be addressed appropriately.

Efficacy of Different Endodontic Irrigant Activation Systems on Smear Layer Removal and Canal Cleanliness: Comparative Scanning Electron Microscopic Study

AIM: This study assessed the effectiveness of 5 different irrigant activation systems on canal cleanliness and removal of smear layer from root canals. METHODS: A total of 110 mandibular premolars with straight root canal were assigned to five groups (n = 20): conventional needle irrigation, passive ultrasonic activation, sonic activation with EndoActivator, negative apical pressure EndoVac (EV), or EDDY system, besides a control group (n = 10). All teeth were prepared to size 40, and irrigated with NaOCl (5.25%) according to the respective technique. Roots were split longitudinally and subjected to scanning electron microscopic analysis. The presence of smear layer and debris was evaluated using 5-grade scoring systems with ×1000 and ×400 magnification, respectively. Data were analyzed at 5%. RESULTS: Regarding the smear layer, activation with EV and ED was significantly more effective than other activation groups (p &lt; 0.05). Activation of the irrigant significantly improved removal of debris (p &lt; 0.05). CONCLUSION: No activation technique was able to eliminate smear layer and debris completely from root canals, nevertheless, EDDY is significantly better in removing debris and smear layer from the apical third of the canal.